Lined brake shoes

ABSTRACT

An apparatus for bonding by heat a layer of friction material to the convex surface of an arcuate platform of a brake shoe having a web extending from the opposed concave surface of the platform, comprises arrangements for locating the shoe in the apparatus and for holding the friction material against the platform. Two electrical heating elements are disposed one on each side of the web and each element has a heating portion which follows the contour of the web and extends along the whole length of the web and a pair of cold tail portions received in a recess in the apparatus and extending away from the platform. The heating portion of each element conveniently takes the form of two radially spaced apart runs joined at one pair of adjacent ends.

United States Patent l 1 1 25 Pritchard June 24, 1975 LINED BRAKE SHOES[75] Inventor: Gethyn James Pritchard, m 'f Truhe Birmingham EnglandAsszsmm Exammerl lv D. He rkamp I Attorney. Agenl, or Fzrm-ScrivenerParker Scrivener [73] Assignee: Girling Limited, Birmingham, d Cl kEngland [22 Filed: Nov. 28. 1973 [571 ABSTRACT An 21 aratus for bondin bheat a la er of friction [211 App. 4l966l matei i l to the convexsfi'fage of an ar uate platform of a brake shoe having a web extendingfrom the op- [30] Foreign Application Priority Data posed concavesurface of the platform, comprises ar- 28 I972 United Kingdom H549551172 rangements for locating the shoe in the apparatus and forholding the friction material against the platform. [52] US. Cl.219/243; 2l9/254; 219/255; O electrical heating elements are disposedone on 219/25q each side of the web and each element has a heating [51Int. Cl. H05!) 3/02 Portion which follows the conwur of the Web and [58]Field of Search 219/254v 255, 259 tends along the whole length of theweb and a pair of 156/499! 583 cold tail portions received in a recessin the apparatus and extending away from the platform. The heating [56]References Cited portion of each element conveniently takes the formUNITED STATES PATENTS of two radially spaced apart runs joined at onepair of adjacent ends. 2l489t496 ll/l949 OBrien 219/243 X 2.662.96012/1953 Williams 219/243 x 5 l 4 ing Fig r s PAT JU 2 ENTED N 4 I975SHEET 3.891.825

LINED BRAKE SHOES This invention relates to lined brake shoes and inparticular to an improved bonding apparatus for the manufacture of linedbrake shoes.

As is known in this art, a brake shoe has a platform of arcuate formwith a web extending from its inner concave surface, the frictionmaterial being generally preformed to the shape of the outer convexplatform surface, but of short arcuate length. It is known to secure thefriction material to the shoe to provide a lined shoe by bonding thematerial to the shoe under heat and for this purpose it has previouslybeen proposed to use two pairs of individual heating elements one pairbeing disposed in each side of the web and the elements of each pairbeing radially spaced apart. With the need under modern conditions tobond quickly, it has been found however, that the shoe was not heateduniformly and that either one end portion of the lining was notadequately bonded to the shoe or that the central portion of the liningthough bonded to the shoe was partly burned and its frictional operatingcharacteristics unacceptably reduced. The electrical heating elementshave heating portions and tail portions, the connections of the tailportions with the supply being safely located within the heatingapparatus. Thus the tail portions of the resistor wire within theinsulating surround which joins the heating portion to the supplyconnection has heretofore had to lie along-side part of the shoe web;that part of the web is therefore less-well heated, as is the adjacentplatform area, resulting in unreliable and possibly un-safe bonding withlarge reject quantities.

According to one feature of the present invention there is provided anapparatus for bonding a layer of friction material to the arcuateplatform of a brake shoe having a web extending from the concave surfaceof the platform, said apparatus comprising shoe locating means locatingthe brake shoe, retaining means for holding a layer of friction materialagainst the platform of the shoe, and a pair of electrical heatingelements disposed one on each side of the web of the shoe and eachhaving a heating portion and at least one tail portion connectedthereto, wherein the heating portions extend adjacent the web of theshoe along the whole length of the web.

According to another feature of the invention, there is provided anapparatus for bonding a layer of friction material to the convex surfaceof an arcuate platform of a brake shoe having a web extending from theconcave surface of the platform, said apparatus comprising an arcuaterecess for receiving the shoe web, locating means for locating the shoewith the web within the recess, retaining means for holding the frictionmaterial against the convex surface of the platform, a pair ofelectrical heating elements disposed one on each side of the recess forheating the shoe web received therein, each heating element having aheating portion and a pair of tail portions, wherein each heatingelement comprises two radially spaced apart, arcuate runs conforminggenerally to the arcuate profile of the recess, one pair of adjacentends of said runs being integrally interconnected by a loop portion andthe other, free pair of ends being turned inwardly away from theplatform, and wherein the heating portion of each element extends ineach run along the whole length of the web.

The shoe web may be either single-walled or double walled. An apparatusin accordance with the invention for bonding a layer of frictionmaterial to the platform of a brake shoe, will be described by way ofexample, with reference to the accompanying drawings in which:

FIG. I is an end elevation of the apparatus,

FIG. 2 is a part section on line II-II of FIG. 1 and FIG. 3 is apre-formed heating element forming part of the apparatus, and

FIG. 4 is a section showing the disposition of the heating element ofFIG. 3 within a heat portion of the apparatus. As seen in FIG. I, theapparatus comprises a support for the shoe consisting of a heat portion1 connected to a base portion 2.

The head portion 1 comprises a central part 4 sandwiched between a pairof intermediate parts 5 and end parts 6. Central part 4 and eachintermediate part 5 have aligned recesses forming radially spacedarcuate channels, 7,7a whilst co-operating intermediate parts 5 and endparts 6 have correspondingly aligned recesses forming radially spacedarcuate channels 8,8a. Between channels 7,7a and channels 8,80 eachintermediate part 5 has an actuate recess for receiving the web 10 ofshoe 11, the platform 12 of which is to be lined with a layer offriction material 13. The web 10 may have a single wall as illustratedor a double wall.

Locating means are provided for positioning the shoe on the support and,as best seen if FIG. 2, comprise pivoted abutments 14 having firstabutment portions I40 for engaging the side edges of the shoe platformto locate the shoe axially on the heat portion 1, clamping portions 14bwhich clamp the shoe platforms against the head, and second abutmentportions Me which engage the side edges of the friction material 13 tocentralize it axially of the platform. Preferably the pivoted abutmentsare protruded at the ends of the shoe and are shouldered to locate andacruately centre the layer of friction material relative to the headportion Retention means in the form of a metal strap I7 connected to atravelling platform below base portion 2 holds friction material 13against the shoe platform 12 during bonding, the platform being movedupon completion of a bonding operation at one intermediate part to anoperational position at the other intermediate part.

One or more end abutments, not shown, are provided to locate the shoerelative to head portion 1. Preferably these end abutments areadjustable so that the apparatus can accept shoes having differentconfigurations.

The pivoted abutment l4 and the end abutments cooperate to centralisethe lining in the head portion 1 whilst permitting offset location ofthe shoe, whereby to obtain the correct relative arcuate disposition oflining to shoe for the particular brake requirement.

Channels 7,7a are interconnected at their terminal portions to receive aheating element 15 (FIG. 3) channels 8,8a are similarly inter-connectedto receive a second heating element 15. Each heating element 15 has hasits tail portions I6 within a recess 19 formed between head portion 1and base portion 2. Thus, the tail portions 16, which are cooler thanthe heating portion 18 of the element, are not aligned with that part ofheat portion 1, receiving the shoe web. The element has two radiallyspaced apart runs 15a 15b joined at one pair of adjacent ends, theother, free ends being turned inwardly away from the platform 12. Thetwo runs 15a 15b permit uniform heating of that part of the head portion1 aligned therewith and thus of the shoe web and its associatedplatform.

3 An advantage of using a single element 15 of the form described isthat failure of the element results in a large measurable temperaturedrop, permitting the apparatus to be stopped automatically. With theprevious proposal using independent elements in each of 5 channels7,7a,8,8a failure of one of the elements was not readily detected bymeans responsive to temperature drop, and bonding could continuenotwithstanding unacceptable temperature gradients resulting in poorbonding.

lt will be appreciated that a tail portion of each of the elements couldbe joined together. Alternatively, the heating portion of one elementcould be directly joined to that of the other element to provide aunitary structure having only two tail portions, one at each end of thestructure.

I claim:

1. An apparatus for bonding a layer of friction material to a brake shoeincluding an arcuate platform having a convex surface for receiving saidlayer of friction material and an opposed concave surface and a web extending from said concave surface of said platform, said apparatuscomprising shoe support means, means for positioning said shoe on saidsupport means comprising a plurality of abutment members each having aclamping portion arranged to clamp said shoe platform against saidsupport means and an abutment portion for locating said layer offriction material on said platform, retaining means for holding saidlayer of friction material against said convex surface of said shoeplatform, and a pair of electrical heating elements disposed one on eachside of said web of the shoe, each heating element having a heatingportion and at least one tail portion connected thereto, wherein saidheating portions extend adjacent said web of said shoe along the wholelength of said web.

2. An apparatus according to claim 1 wherein each of said abutmentmembers includes another abutment portion for locating said shoe on saidsupport.

3. An apparatus according to claim 2, wherein said abutment members areadjustable to receive shoes having different configurations.

4. An apparatus according to claim 1 wherein said support means includesan arcuate recess for receiving said shoe web and wherein each heatingelement has a pair of tail portions and comprises two radially spacedapart, arcuate runs conforming generally to the arcuate profile of saidrecess, one pair of adjacent ends of said runs being integrallyinterconnected by a loop portion and the other, free pair of ends beingturned inwardly away from the platform, and wherein said heating portionof each said element extends in each run along the whole length of saidweb.

5. An apparatus according to claim 4 including means defining a furtherrecess within said apparatus wherein said tail portions of said heatingelements are received within said further recess in said apparatus.

1. An apparatus for bonding a layer of friction material to a brake shoeincluding an arcuate platform having a convex surface for receiving saidlayer of friction material and an opposed concave surface and a webextending from said concave surface of said platform, said apparatuscomprising shoe support means, means for positioning said shoe on saidsupport means comprising a plurality of abutment members each having aclamping portion arranged to clamp said shoe platform against saidsupport means and an abutment portion for locating said layer offriction material on said platform, retaining means for holding saidlayer of friction material against said convex surface of said shoeplatform, and a pair of electrical heating elements disposed one on eachside of said web of the shoe, each heating element having a heatingportion and at least one tail portion connected thereto, wherein saidheating portions extend adjacent said web of said shoe along the wholelength of said web.
 2. An apparatus according to claim 1 wherein each ofsaid abutment members includes another abutment portion for locatingsaid shoe on said support.
 3. An apparatus according to claim 2, whereinsaid abutment members are adjustable to receive shoes having differentconfigurations.
 4. An apparatus according to claim 1 wherein saidsupport means includes an arcuate recess for receiving said shoe web andwherein each heating element has a pair of tail portions and comprisestwo radially spaced apart, arcuate runs conforming generally to thearcuate profile of said recess, one pair of adjacent ends of said runsbeing integrally interconnected by a loop portion and the other, freepair of ends being turned inwardly away from the platform, and whereinsaid heating portion of each said element extends in each run along thewhole length of said web.
 5. An apparatus according to claim 4 includingmeans defining a further recess within said apparatus wherein said tailportions of said heating elements are received within said furtherrecess in said apparatus.